This invention relates to automatic plotting systems and more particularly to those plotting systems used with mobile displays such as marine radar displays and the like.
In prior art radar systems, plotting of the tracks of other ships or vehicles is done manually. For example, the relative positions of other vehicles are marked on the faceplate of the radar display at intervals of time determined by the operator. Parallax errors are introduced by the distance between the plotting surface and the radar florescent screen. These errors may be eliminated by reflective plotters. However, reflective plotters usually create undesirable reflections which mask visibility and obstruct the use of the radar display. Futhermore, manual plotting, using a grease pencil, is time consuming and distracts the operator from other duties such as navigation of the ship. The situation is aggravated when there are many marine targets and accurate determination of their changing courses requires frequent plotting.